docs: Add new section "Running a Node"

[amaury1093]

Description

ref: #7657
ref: #7403

rendered

• Move interfaces/keyring.md to run-node/keyring.md, and update content.
• Move using-the-sdk/quickstart.md to run-node/run-node.md and run-node/interact-node.md, and update content.

---

Before we can merge this PR, please make sure that all the following items have been
checked off. If any of the checklist items are not applicable, please leave them but
write a little note why.

• Targeted PR against correct branch (see CONTRIBUTING.md)
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Code follows the module structure standards.
• Wrote unit and integration tests
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added relevant godoc comments.
• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md
• Re-reviewed Files changed in the Github PR explorer
• Review Codecov Report in the comment section below once CI passes

[robert-zaremba]

Left few comments and suggestions.

[clevinson]

Few minor comments, but otherwise lgtm!

[codecov]

Codecov Report

Merging #7701 into master will increase coverage by 0.02%.
The diff coverage is 75.00%.

@@            Coverage Diff             @@
##           master    #7701      +/-   ##
==========================================
+ Coverage   54.19%   54.21%   +0.02%     
==========================================
  Files         610      609       -1     
  Lines       38872    38872              
==========================================
+ Hits        21065    21076      +11     
+ Misses      15650    15638      -12     
- Partials     2157     2158       +1     

[amaury1093]

Thanks a bunch @robert-zaremba @alessio @clevinson for this review, it was very helpful! I believe I addressed all comments, would appreciate another round of review.